use crate::editor::{Action, Breakpoint};
use crate::{align_view, Align, Editor};
use dap::requests::DisconnectArguments;
use helix_core::Selection;
use helix_dap::{self as dap, Client, ConnectionType, Payload, Request, ThreadId};
use helix_lsp::block_on;
use log::warn;
use serde_json::json;
use std::fmt::Write;
use std::path::PathBuf;

#[macro_export]
macro_rules! debugger {
    ($editor:expr) => {{
        match &mut $editor.debugger {
            Some(debugger) => debugger,
            None => return,
        }
    }};
}

// general utils:
pub fn dap_pos_to_pos(doc: &helix_core::Rope, line: usize, column: usize) -> Option<usize> {
    // 1-indexing to 0 indexing
    let line = doc.try_line_to_char(line - 1).ok()?;
    let pos = line + column.saturating_sub(1);
    // TODO: this is probably utf-16 offsets
    Some(pos)
}

pub async fn select_thread_id(editor: &mut Editor, thread_id: ThreadId, force: bool) {
    let debugger = debugger!(editor);

    if !force && debugger.thread_id.is_some() {
        return;
    }

    debugger.thread_id = Some(thread_id);
    fetch_stack_trace(debugger, thread_id).await;

    let frame = debugger.stack_frames[&thread_id].first().cloned();
    if let Some(frame) = &frame {
        jump_to_stack_frame(editor, frame);
    }
}

pub async fn fetch_stack_trace(debugger: &mut Client, thread_id: ThreadId) {
    let (frames, _) = match debugger.stack_trace(thread_id).await {
        Ok(frames) => frames,
        Err(_) => return,
    };
    debugger.stack_frames.insert(thread_id, frames);
    debugger.active_frame = Some(0);
}

pub fn jump_to_stack_frame(editor: &mut Editor, frame: &helix_dap::StackFrame) {
    let path = if let Some(helix_dap::Source {
        path: Some(ref path),
        ..
    }) = frame.source
    {
        path.clone()
    } else {
        return;
    };

    if let Err(e) = editor.open(&path, Action::Replace) {
        editor.set_error(format!("Unable to jump to stack frame: {}", e));
        return;
    }

    let (view, doc) = current!(editor);

    let text_end = doc.text().len_chars().saturating_sub(1);
    let start = dap_pos_to_pos(doc.text(), frame.line, frame.column).unwrap_or(0);
    let end = frame
        .end_line
        .and_then(|end_line| dap_pos_to_pos(doc.text(), end_line, frame.end_column.unwrap_or(0)))
        .unwrap_or(start);

    let selection = Selection::single(start.min(text_end), end.min(text_end));
    doc.set_selection(view.id, selection);
    align_view(doc, view, Align::Center);
}

pub fn breakpoints_changed(
    debugger: &mut dap::Client,
    path: PathBuf,
    breakpoints: &mut [Breakpoint],
) -> Result<(), anyhow::Error> {
    // TODO: handle capabilities correctly again, by filtering breakpoints when emitting
    // if breakpoint.condition.is_some()
    //     && !debugger
    //         .caps
    //         .as_ref()
    //         .unwrap()
    //         .supports_conditional_breakpoints
    //         .unwrap_or_default()
    // {
    //     bail!(
    //         "Can't edit breakpoint: debugger does not support conditional breakpoints"
    //     )
    // }
    // if breakpoint.log_message.is_some()
    //     && !debugger
    //         .caps
    //         .as_ref()
    //         .unwrap()
    //         .supports_log_points
    //         .unwrap_or_default()
    // {
    //     bail!("Can't edit breakpoint: debugger does not support logpoints")
    // }
    let source_breakpoints = breakpoints
        .iter()
        .map(|breakpoint| helix_dap::SourceBreakpoint {
            line: breakpoint.line + 1, // convert from 0-indexing to 1-indexing (TODO: could set debugger to 0-indexing on init)
            ..Default::default()
        })
        .collect::<Vec<_>>();

    let request = debugger.set_breakpoints(path, source_breakpoints);
    match block_on(request) {
        Ok(Some(dap_breakpoints)) => {
            for (breakpoint, dap_breakpoint) in breakpoints.iter_mut().zip(dap_breakpoints) {
                breakpoint.id = dap_breakpoint.id;
                breakpoint.verified = dap_breakpoint.verified;
                breakpoint.message = dap_breakpoint.message;
                // TODO: handle breakpoint.message
                // TODO: verify source matches
                breakpoint.line = dap_breakpoint.line.unwrap_or(0).saturating_sub(1); // convert to 0-indexing
                                                                                      // TODO: no unwrap
                breakpoint.column = dap_breakpoint.column;
                // TODO: verify end_linef/col instruction reference, offset
            }
        }
        Err(e) => anyhow::bail!("Failed to set breakpoints: {}", e),
        _ => {}
    };
    Ok(())
}

impl Editor {
    pub async fn handle_debugger_message(&mut self, payload: helix_dap::Payload) -> bool {
        use helix_dap::{events, Event};

        let debugger = match self.debugger.as_mut() {
            Some(debugger) => debugger,
            None => return false,
        };
        match payload {
            Payload::Event(event) => {
                let event = match Event::parse(&event.event, event.body) {
                    Ok(event) => event,
                    Err(dap::Error::Unhandled) => {
                        log::info!("Discarding unknown DAP event '{}'", event.event);
                        return false;
                    }
                    Err(err) => {
                        log::warn!("Discarding invalid DAP event '{}': {err}", event.event);
                        return false;
                    }
                };
                match event {
                    Event::Stopped(events::StoppedBody {
                        thread_id,
                        description,
                        text,
                        reason,
                        all_threads_stopped,
                        ..
                    }) => {
                        let all_threads_stopped = all_threads_stopped.unwrap_or_default();

                        if all_threads_stopped {
                            if let Ok(response) =
                                debugger.request::<dap::requests::Threads>(()).await
                            {
                                for thread in response.threads {
                                    fetch_stack_trace(debugger, thread.id).await;
                                }
                                select_thread_id(self, thread_id.unwrap_or_default(), false).await;
                            }
                        } else if let Some(thread_id) = thread_id {
                            debugger.thread_states.insert(thread_id, reason.clone()); // TODO: dap uses "type" || "reason" here

                            // whichever thread stops is made "current" (if no previously selected thread).
                            select_thread_id(self, thread_id, false).await;
                        }

                        let scope = match thread_id {
                            Some(id) => format!("Thread {}", id),
                            None => "Target".to_owned(),
                        };

                        let mut status = format!("{} stopped because of {}", scope, reason);
                        if let Some(desc) = description {
                            write!(status, " {}", desc).unwrap();
                        }
                        if let Some(text) = text {
                            write!(status, " {}", text).unwrap();
                        }
                        if all_threads_stopped {
                            status.push_str(" (all threads stopped)");
                        }

                        self.set_status(status);
                    }
                    Event::Continued(events::ContinuedBody { thread_id, .. }) => {
                        debugger
                            .thread_states
                            .insert(thread_id, "running".to_owned());
                        if debugger.thread_id == Some(thread_id) {
                            debugger.resume_application();
                        }
                    }
                    Event::Thread(_) => {
                        // TODO: update thread_states, make threads request
                    }
                    Event::Breakpoint(events::BreakpointBody { reason, breakpoint }) => {
                        match &reason[..] {
                            "new" => {
                                if let Some(source) = breakpoint.source {
                                    self.breakpoints
                                        .entry(source.path.unwrap()) // TODO: no unwraps
                                        .or_default()
                                        .push(Breakpoint {
                                            id: breakpoint.id,
                                            verified: breakpoint.verified,
                                            message: breakpoint.message,
                                            line: breakpoint.line.unwrap().saturating_sub(1), // TODO: no unwrap
                                            column: breakpoint.column,
                                            ..Default::default()
                                        });
                                }
                            }
                            "changed" => {
                                for breakpoints in self.breakpoints.values_mut() {
                                    if let Some(i) =
                                        breakpoints.iter().position(|b| b.id == breakpoint.id)
                                    {
                                        breakpoints[i].verified = breakpoint.verified;
                                        breakpoints[i].message = breakpoint
                                            .message
                                            .clone()
                                            .or_else(|| breakpoints[i].message.take());
                                        breakpoints[i].line =
                                            breakpoint.line.map_or(breakpoints[i].line, |line| {
                                                line.saturating_sub(1)
                                            });
                                        breakpoints[i].column =
                                            breakpoint.column.or(breakpoints[i].column);
                                    }
                                }
                            }
                            "removed" => {
                                for breakpoints in self.breakpoints.values_mut() {
                                    if let Some(i) =
                                        breakpoints.iter().position(|b| b.id == breakpoint.id)
                                    {
                                        breakpoints.remove(i);
                                    }
                                }
                            }
                            reason => {
                                warn!("Unknown breakpoint event: {}", reason);
                            }
                        }
                    }
                    Event::Output(events::OutputBody {
                        category, output, ..
                    }) => {
                        let prefix = match category {
                            Some(category) => {
                                if &category == "telemetry" {
                                    return false;
                                }
                                format!("Debug ({}):", category)
                            }
                            None => "Debug:".to_owned(),
                        };

                        log::info!("{}", output);
                        self.set_status(format!("{} {}", prefix, output));
                    }
                    Event::Initialized(_) => {
                        // send existing breakpoints
                        for (path, breakpoints) in &mut self.breakpoints {
                            // TODO: call futures in parallel, await all
                            let _ = breakpoints_changed(debugger, path.clone(), breakpoints);
                        }
                        // TODO: fetch breakpoints (in case we're attaching)

                        if debugger.configuration_done().await.is_ok() {
                            self.set_status("Debugged application started");
                        }; // TODO: do we need to handle error?
                    }
                    Event::Terminated(terminated) => {
                        let restart_args = if let Some(terminated) = terminated {
                            terminated.restart
                        } else {
                            None
                        };

                        let disconnect_args = Some(DisconnectArguments {
                            restart: Some(restart_args.is_some()),
                            terminate_debuggee: None,
                            suspend_debuggee: None,
                        });

                        if let Err(err) = debugger.disconnect(disconnect_args).await {
                            self.set_error(format!(
                                "Cannot disconnect debugger upon terminated event receival {:?}",
                                err
                            ));
                            return false;
                        }

                        match restart_args {
                            Some(restart_args) => {
                                log::info!("Attempting to restart debug session.");
                                let connection_type = match debugger.connection_type() {
                                    Some(connection_type) => connection_type,
                                    None => {
                                        self.set_error("No starting request found, to be used in restarting the debugging session.");
                                        return false;
                                    }
                                };

                                let relaunch_resp = if let ConnectionType::Launch = connection_type
                                {
                                    debugger.launch(restart_args).await
                                } else {
                                    debugger.attach(restart_args).await
                                };

                                if let Err(err) = relaunch_resp {
                                    self.set_error(format!(
                                        "Failed to restart debugging session: {:?}",
                                        err
                                    ));
                                }
                            }
                            None => {
                                self.debugger = None;
                                self.set_status(
                                    "Terminated debugging session and disconnected debugger.",
                                );
                            }
                        }
                    }
                    Event::Exited(resp) => {
                        let exit_code = resp.exit_code;
                        if exit_code != 0 {
                            self.set_error(format!(
                                "Debuggee failed to exit successfully (exit code: {exit_code})."
                            ));
                        }
                    }
                    ev => {
                        log::warn!("Unhandled event {:?}", ev);
                        return false; // return early to skip render
                    }
                }
            }
            Payload::Response(_) => unreachable!(),
            Payload::Request(request) => {
                let reply = match Request::parse(&request.command, request.arguments) {
                    Ok(Request::RunInTerminal(arguments)) => {
                        let config = self.config();
                        let Some(config) = config.terminal.as_ref() else {
                            self.set_error("No external terminal defined");
                            return true;
                        };

                        let process = match std::process::Command::new(&config.command)
                            .args(&config.args)
                            .arg(arguments.args.join(" "))
                            .spawn()
                        {
                            Ok(process) => process,
                            Err(err) => {
                                self.set_error(format!(
                                    "Error starting external terminal: {}",
                                    err
                                ));
                                return true;
                            }
                        };

                        Ok(json!(dap::requests::RunInTerminalResponse {
                            process_id: Some(process.id()),
                            shell_process_id: None,
                        }))
                    }
                    Err(err) => Err(err),
                };

                if let Some(debugger) = self.debugger.as_mut() {
                    debugger
                        .reply(request.seq, &request.command, reply)
                        .await
                        .ok();
                }
            }
        }
        true
    }
}
